Shelf life of lens coating

Hello, theoretically, but for an old man with good quality, there is generally no big problem. Although the previous coating technology is not as good as it is now, some lenses are durable and there is nothing to say. It's a pity that I haven't discussed this problem much with others and can't give you much advice. Look at it with the naked eye first, and you can't see any obvious problems. Just like Olympus's early OM55/ 1.2 rare earth version of big eyes, after more than 20 years of "volatilization", the lens will turn yellow, but the quality is good and it is expensive to sell. Or you can tell me what lens you are going to watch again.